Need Passive Subs- Ideas?

I am using a set of Talon Khorus speakers, which I am using just for bottom end with a set of Unity Audio for the uppers. A DQ-LP1 crossover works well to blend them. It sounds great using that combo, but I need to sell the Talons due to the size and it just seems like a waste of an expensive speaker(just upgraded the networks too) to utilize for bass only. Anyways, I am looking for a good alternative as I do not want powered subs, I will use an acoustat amp to drive them. Would like to keep them against the wall due to somewhat limited space. Not looking for huge 15" drivers, as I prefer good tight bass, but really like the lows that the 10" Talons can do. I am a furniture maker, so construction shouldn't be an issue. Any good designs/plans or might even consider already made passive subs, would work out as well.
How about theses?

Not afiliated with the seller in any way......

Look for a used RA Labs passive sub. I have two, and they sound better then any thing powered. Your amp speaker cable goes to the sub and it is wired to pass the highs thru to you main speakers. By the way the RA stands for Roy Allison who did all the design work for a company that named itself RA Labs. I have a complete sets of RA's, centers, mini's and minitor's. Roy has got one of the best ears in the business, not so with running businesses.
Why not Talon ROCs? There are passive ones.